Insulin Activation Time: awake vs asleep

In the past few months we have had to deal with a lot of night peaks. We are very aggressive on peaks and stack quickly, based on our known Insulin Activation Time.

But we got caught several times overstacking at night: we would stack on schedule when not seeing expected insulin action, then get caught by a later drop, resulting in an over correction.

So we started tracking Insulin Activation Time for time asleep vs awake, and found very significant differences. Our normal IAT awake is 45 minutes, but out normal IAT asleep is 1 hour 15 minutes, a big difference!

As a note, in both cases we can see significant variations in IAT when dealing with large peaks.

[EDIT]: to clarify naming, this is not DIA [Duration of Insulin Activation] but how long it takes before my son “turns the corner” after an insulin injection. This is critical data for us because this allows us to plan for meals, and it also allows us to stack aggressively when we are not satisfied with the consequences of a bolus correction.


On MM pump, the AIT is 2-8 hours, 1hour increment, and used by wizard. (Which I don’t use). So surprised you can set that low (omnipod?).

Are you saying during day, a bolus is delivered, then gone in 45 minutes? And 75 minutes overnight ? What insulin are you using? That sounds like Afrezza !

When correcting high BGs, I think it requires more insulin due to resistance. The cells are not eager to take on more glucose when they are full !

I think he is saying the activation time, how long it takes before the insulin starts to work. Not the duration.

On the OmniPod, duration can be set from 2 hours to 6 hours, in 30 minute increments. But I think he is just saying it takes longer for insulin to become active at night.

Michel, that doesn’t surprise me. When you are active your muscles contractions are more actively moving the insulin from the infusion site, your heart is beating faster and your blood is moving faster which accelerates absorption, your activity is increasing your insulin sensitivity. It is very likely it is faster for K during the day.

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Hey there Michel. I hope your travels are going well.

I’d also like to hear specifically how you track/determine Insulin Activation Time/IAT?

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Hmmm, AIT vs IAT.

Minimed 523 only has Active Insulin Time (AIT). No option for IAT, so that’s a new concept for me.
Not sure about newer models.


There is nothing on the OmniPod specifically for insulin ACTIVATION time either. It’s just something Michel is looking at.


My fault, sorry. I defined IAT, it is not DIA, duration of insulin action. IAT is the time it takes for insulin to become active with us, what sugarsurfers call turning the corner.

We stack very aggressively. IAT (along with other durations, such as how long insulin activation remains high) allows us to stack reasonably safely. IAT is also what we use to plan meals: if in range, time of prebolus + IAT = meal time.


I have noticed this for quite some time. When I wake up to a high alarm (>180 at night) I hit it pretty hard. But I don’t see any evidence that I’ve taken a boatload of insulin until the next morning. Sometimes 4+ hours!

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Interesting. I know about turning the corner, or “the bend”. But never considered tracking it at different times of the day.

Another thing I consider is “food on board”, especially fat, proteins, which may appear to slow down the IAT, and mute the bend.


@MM2 , this is really interesting to me. How do you quantify that?

Pretty much WAG. But I think about when I last ate, how much was fat, protein, what activity level has been, IOB, what is current Dexcom trend, and a number pops into my head !

I also eat a lot of the same things, and fill my plate with approx same amount and ratio of carbs, fats, proteins. A carry over from the old exchanges.

Most of my meal boluses are 3-4 units, TDD around 18-20.